@w:500px;
@h:300px;
p{
    color:green;
}
.app{
    width: @w;
    height: @h;
    border:1px solid red;
    display: flex;
    background:red;
    .react {
        width: 200px;
        height: 200px;
        background: url('../images/react.png') no-repeat;
        background-size: cover;
    }

    .vue {
        width: 200px;
        height: 200px;
        background: url('../images/vue.png') no-repeat;
        background-size: cover;
    }
}